How wind formed largest dust deposit on Earth

China's Loess Plateau -- the largest dust deposit in Earth -- was formed by wind alternately depositing dust or removing dust over the last 2.6 million years, according to geoscientists from University of Arizona.

The study is the first to explain how the steep-fronted plateau formed.

About the size of the state of Arizona, the Loess Plateau is the largest accumulation of dust on Earth.

Deposits of wind-blown dust known as "loess" generally create good agricultural soil and are found in many parts of the world, including the US Midwest.

"Wind blew dust from what is now the Mu Us Desert into the huge pile of consolidated dust known as the Loess Plateau," said lead author Paul Kapp, professor of geosciences.

Just as a leaf blower clears an area by piling leaves up along the edge, the wind did the same thing with the dust that was once in the Mu Us Desert.

"If the blower keeps blowing the leaves, they move backward and the pile of leaves gets bigger," Kapp said. "There is a boundary between the area of leaves and no leaves."

The team also found that, just as a leaf blower moves a pile of leaves away from itself, wind scours the face of the plateau so forcefully that the plateau is slowly moving downwind.

"You have a dust-fall event and then you have a wind event that blows some of the dust away," Kapp said. "The plateau is not static. It's moving in a windward direction."

Linear ridges on the top of the Loess Plateau are also sculpted by the wind, the researchers found.

"The significance of wind erosion shaping the landscape is generally unappreciated. It is more important than previously thought," the authors noted.

The paper is forthcoming in the journal Geology.